From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
RT-users <linux-rt-users@vger.kernel.org>,
Carsten Emde <cbe@osadl.org>
Subject: [patch RT 5/7] slab: Prevent local lock deadlock
Date: Wed, 11 Jul 2012 22:05:19 -0000 [thread overview]
Message-ID: <20120711215612.055300422@linutronix.de> (raw)
In-Reply-To: 20120711214552.036760674@linutronix.de
[-- Attachment #1: slab-fix-local-lock-wreckage.patch --]
[-- Type: text/plain, Size: 1931 bytes --]
On RT we avoid the cross cpu function calls and take the per cpu local
locks instead. Now the code missed that taking the local lock on the
cpu which runs the code must use the proper local lock functions and
not a simple spin_lock(). Otherwise it deadlocks later when trying to
acquire the local lock with the proper function.
Reported-and-tested-by: Chris Pringle <chris.pringle@miranda.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
mm/slab.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)
Index: linux-stable-rt/mm/slab.c
===================================================================
--- linux-stable-rt.orig/mm/slab.c
+++ linux-stable-rt/mm/slab.c
@@ -743,8 +743,26 @@ slab_on_each_cpu(void (*func)(void *arg,
{
unsigned int i;
+ get_cpu_light();
for_each_online_cpu(i)
func(arg, i);
+ put_cpu_light();
+}
+
+static void lock_slab_on(unsigned int cpu)
+{
+ if (cpu == smp_processor_id())
+ local_lock_irq(slab_lock);
+ else
+ local_spin_lock_irq(slab_lock, &per_cpu(slab_lock, cpu).lock);
+}
+
+static void unlock_slab_on(unsigned int cpu)
+{
+ if (cpu == smp_processor_id())
+ local_unlock_irq(slab_lock);
+ else
+ local_spin_unlock_irq(slab_lock, &per_cpu(slab_lock, cpu).lock);
}
#endif
@@ -2692,10 +2710,10 @@ static void do_drain(void *arg, int cpu)
{
LIST_HEAD(tmp);
- spin_lock_irq(&per_cpu(slab_lock, cpu).lock);
+ lock_slab_on(cpu);
__do_drain(arg, cpu);
list_splice_init(&per_cpu(slab_free_list, cpu), &tmp);
- spin_unlock_irq(&per_cpu(slab_lock, cpu).lock);
+ unlock_slab_on(cpu);
free_delayed(&tmp);
}
#endif
@@ -4163,9 +4181,9 @@ static void do_ccupdate_local(void *info
#else
static void do_ccupdate_local(void *info, int cpu)
{
- spin_lock_irq(&per_cpu(slab_lock, cpu).lock);
+ lock_slab_on(cpu);
__do_ccupdate_local(info, cpu);
- spin_unlock_irq(&per_cpu(slab_lock, cpu).lock);
+ unlock_slab_on(cpu);
}
#endif
next prev parent reply other threads:[~2012-07-11 22:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-11 22:05 [patch RT 0/7] Various fixes for the stable RT series - part I Thomas Gleixner
2012-07-11 22:05 ` [patch RT 1/7] Latency histogramms: Cope with backwards running local trace clock Thomas Gleixner
2012-07-11 22:05 ` [patch RT 2/7] Latency histograms: Adjust timer, if already elapsed when programmed Thomas Gleixner
2012-07-11 22:05 ` [patch RT 3/7] Disable RT_GROUP_SCHED in PREEMPT_RT_FULL Thomas Gleixner
2012-07-12 2:36 ` Mike Galbraith
2012-07-11 22:05 ` [patch RT 4/7] Latency histograms: Detect another yet overlooked sharedprio condition Thomas Gleixner
2012-07-11 22:05 ` Thomas Gleixner [this message]
2012-07-11 22:05 ` [patch RT 6/7] fs, jbd: pull your plug when waiting for space Thomas Gleixner
2012-07-11 22:05 ` [patch RT 7/7] perf: Make swevent hrtimer run in irq instead of softirq Thomas Gleixner
2012-07-11 23:31 ` [patch RT 0/7] Various fixes for the stable RT series - part I Steven Rostedt
2012-07-12 8:49 ` Thomas Gleixner
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